Total synthesis of yeast alanine tRNA gene is being studied further. Total synthesis of the gene for E. coli tyrosine suppressor tRNA gene is in progress. Methodology for rapid and efficient synthesis of deoxypolynucleotide segments is under intensive investigation. The complementary problem of ligase-catalyzed joining is being studied using DNA-ligases from different sources. Using the totally synthetic DNA's of defined sequence, replication by DNA polymerases (I and II) and transcription by RNA polymerases are under investigation. The question of promoter sequences for transcription is being studied by phi 80psuIII DNA and synthetic complementary deoxyribopolynucleotides. Similarly, the sequences of the terminator region in the E. coli tyrosine gene of phi 80 psuIII DNA is being determined--the sequence of 23 nucleotides is already known. For possible biological studies, ligase-catalyzed end- to-end joining (recently discovered in this laboratory) is under further examination in order to join short synthetic gene to lambda DNA.